Effect of Active Site Mutation Phe 93 → Trp in the Horse Liver Alcohol Dehydrogenase Enzyme on Catalysis:  A Molecular Dynamics Study

2002 ◽  
Vol 106 (51) ◽  
pp. 13111-13113 ◽  
Author(s):  
C. Kalyanaraman ◽  
Steven D. Schwartz
Keyword(s):  
Molecular Dynamics ◽  
Alcohol Dehydrogenase ◽  
Active Site ◽  
Site Mutation ◽  
Horse Liver Alcohol Dehydrogenase ◽  
Liver Alcohol Dehydrogenase ◽  
Horse Liver ◽  
Dehydrogenase Enzyme

scholarly journals Enantioselective affinity labelling of horse liver alcohol dehydrogenase. Correlation of inactivation kinetics with the three-dimensional structure of the enzyme

1983 ◽  
Vol 211 (2) ◽  
pp. 391-396 ◽  
Author(s):  
K H Dahl ◽  
H Eklund ◽  
J S McKinley-McKee
Keyword(s):  
Alcohol Dehydrogenase ◽  
Active Site ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Inactivation Kinetics ◽  
Horse Liver Alcohol Dehydrogenase ◽  
Three Dimensional Structure ◽  
Liver Alcohol Dehydrogenase ◽  
Horse Liver ◽  
Affinity Labelling

Kinetic data for the inactivation of horse liver alcohol dehydrogenase with S-2-chloro-3-(imidazol-5-yl)propionate at pH8.2 were correlated with the three-dimensional structure of the enzyme. The R-2-chloro-3-(imidazol-5-yl)propionate enantiomer did not inactivate the enzyme, and the reaction is thus enantioselective. Inactivation follows an affinity-labelling mechanism where a reversible complex is formed before the irreversible alkylation and inactivation of the enzyme. A reversible complex is also formed with the non-inactivating enantiomer, and this shows that the selectivity occurs at the irreversible step. By using a computer-controlled display system, models of the two enantiomers of 2-chloro- and 2-bromo-3-(imidazol-5-yl)propionate were built into a model of the enzyme so that the imidazole moiety was liganded to the active-site metal, while the carboxylate group interacted with the general anion-binding site. The conformation of the imidazole derivatives and their orientation in the active site were adjusted to minimize unfavourable steric interactions. It was clear that alkylation of cysteine-46 could proceed with the S-enantiomer bound in this way, but not with the R-enantiomer. Model building thus agrees with the inactivation kinetics and indicates the structural origin of the enantioselectivity.

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